Test clip



Dec. 31, 1963 J. M. KlKTA 3,116,101

1 TEST CLIP Filed April 6, 1960 IIIIMIIIIIH ml m I H'HH'Hn.

IN VEN TOR.

iii!!! 11 BY Iljgllllll 16 W W United States Patent .1 3,116,101 TESTCLIP John M. Kiirta, Downers Grove, 11]., assignor to Grayhili, Inc., LaGrange, 111., a corporation of Illinois Filed Apr. 6, 1960, Ser. No.20,492 2 Claims. (Cl. 339-258) This invention relates to holding devicesfor use as electrical connectors, and more particularly to improvedminiature electrical test clips.

The manufacture and maintenance of electrical products involves a greatdeal of testing which requires that such products be electricallyconnected in a circuit containing an electric meter. Temporary testconnections of resistors, capacitors, transistors and other componentshaving pigtail type leads are commonly made by means of electrical testclips. Test clips of the type designed for panel mounting on testequipment and also those designed for use in bread-board work must bedurable and yet allow for rapid connections without requiring muchattention on the part of the user. In addition, they should be capableof handling a range of wire sizes or other objects without adjustment,and some means of varying the clamping force should be provided.Although a variety of test clips are available, they are not entirelysatisfactory from the standpoint of size, cost and flexibility of use.

Accordingly, it is an object of the present invention to provide a testclip which is strong and durable and yet easily made in miniature formfor a variety of mountings.

Anotherobject of the invention is to provide a simple, strong holdingdevice to which rapid electrical and/or mechanical connections ofobjects of various sizes and shapes may be securely made without manualopening and closing of jaws.

A further object is to provide a simple, strong test clip which iseasily adjustable in tension and which is readily adaptable to receive aplurality of wires in a variety of engagements.

A feature of the invention is the provision of a holding deviceincluding a rigid post and a flexible contact portion assembled to thepost by the stem of post provided for mounting the post on a chassis.

Another feature of the invention is the provision of a miniature testclip including a rigid member with a post portion and a threadedmounting stem, and one or more resilient contact members having openingsfor receiving the stem and shaped to be forced toward contact surfaceson the post portion of the rigid member when drawn thereto by a nut onthe stem.

In the accompanying drawing:

FIG. 1 is a greatly enlarged perspective view of a test clip constructedin accordance with the invention and mounted on a printed circuit board;

FIG. 2 is a greatly enlarged side elevational view of the test clip ofFIG. 1;

FIG. 3 is a front elevational view of the same;

FIG. 4 is a top plan view of the same;

FIG. 5 is an elevational side view of a test clip having two springmembers showing a wire inserted therein;

FIG. 6 is .a side elevational view of a modified form of the test clipin accordance with the invention; and

FIG. 7 is a side elevational view of still another form of theinvention.

The invention provides a miniature electrical test clip 3,116,1dlPatented Dec. 31, 1963 ice for obtaining rapid, temporary testconnections to a wire lead. The test clip comprises two basic parts; astrong, rigid elongated member having a head or post portion and a stemmounting portion, and a bent resilient member received against andsupported by the former. The resilient member has a curved, aperturedbase portion which is received on the stem portion, and a flexible, wireengaging contact portion which -is urged towards a contact surface ofthe rigid member by the flattening of the base portion between ashoulder on the rigid memher and either a nut received on the stemportion or the surface on which the rigid member is mounted. A stop maybe formed either on the rigid member or on the resilient member torestrain movement of the wire lead as it is positioned on the clip.Several resilient members may be provided on one rigid member when aplurality of wires are to be connected thereto. The clip may be used tosupport various objects, and the resilient member may be variouslyshaped to provide different degrees of engagement with the wires orother objects to be held.

Referring now in more detail to the drawing, FIG. 1 illustrates aminiature test clip 10 mounted on a printed circuit board 11, with thelead wire 12 of a small pigtail component being inserted therein byhand. The thumb and forefinger of an adult illustrate the diminutivesize of the test clip, which in the particular embodiments illustratedhas an overall length of about W of an inch.

The test clip of FIG. 1 is shown greatly enlarged in the side, front andtop view of FIGS. 2, 3 and 4 respectively. The principal supportingelement of the test clip is a rigid elongated member 13 with an enlargedupper post or head portion 14 and a reduced lower stem portion 16. Therigid member 13 may be made of nonferrous materials having goodconductivity, such as nickel plated brass or other suitable materials.Head 14 is square shaped and therefore provides four substantially fiatsides any or all of which may serve as electrical contact surfaces.However, other head shapes, such as triangular or hexagonal, may be usedas desired. The reduced portion or stem 16 carries an external threadadapted to receive hex nuts 17 and 18 for mounting the bolt on a panelmember such as circuit board 11 or to screwably mount the bolt in athreaded hole provided in a meter housing or other mounting devices. Thejunction of the threaded stem and the bolt head forms ashoulder 19 whosespacing from the upper surface of nut 18 depends upon the extent towhich the bolt is screwed'into board 11 and the corresponding setting of'hex nuts 17 and 13.

A resilient or spring-like member 21 provides the opposing jaw of thetest clip. This member may be readily stamped from a thin, fiat piece ofsuitable spring sheet metal such as heat treated beryllium copper shapedinto a generally L-shaped configuration comprising two principalportions, a bowed base portion 22 and an upwardly extending contactportion 23. An aperture or hole 24 is formed in the center of baseportion 22 which receives stem 16 therethrough in mounting spring member21 on bolt 13. When thus mounted it is to be noted that base portion 22is bowed away from, or convexly disposed with respect to shoulder 19 ofhead 14. Since spring 21 is entirely resilient throughout, it will beseen that screwing the bolt down into board 11 or drawing 3 nut 18 uptowards shoulder 19 will flex or flatten the bowed base portion. Thisflattening of the base portion in turn urges contact portion 23 morefirmly against the contact face of head 14. Thus, it is a simple matterto vary the Spring tension of the test clip.

Normally, both the bolt and the spring member are utilized aselectrically conducting members in the test clip since they will alwaysbe in firm mechanical contact with one another. But for certainapplications it may be preferred to construct the bolt of insulatingmaterial, such as hard plastic, and rely solely on the spring member toprovide the conducting path. Since the bolt is made rigid and need notbe reduced in size to the extent of the spring member, such materialsare entirely compatible with the test clip of the invention.

The upper or contact portion 23 of the resilient member 21 can be shapedas desired to provide the particular engagement best suited for the sizeand type of com ponents being inserted. Thus, the contact portion 23shown in the embodiment of FIGS. 1-5 has a flared-out portion 25 at theupper end thereof which allows a wedging action to facilitate insertionof a wire between spring 21 and the adjacent contact surface of head 14.Immediately below this flared-out portion there is a generally straightor flat wire engaging portion which terminates in an inwardly depressedstop portion 26 shaped to form a projection to limit downward movementof the wire (FIG. The depth of this depression depends upon the range ofwire sizes to be tested and is, of course, limited by the smallest wiresize for which the clip is to be used. The remaining portion of thespring member, between depression 26 and base portion 22, is angularlydisposed with respect to the adjacent contact face of head 14 and servesto transmit the stresses resulting from the flexure of the base portion22 to the points of actual engagement of the spring member with aninserted wire.

A modified form of the invention is illustrated in FIG. 6 whereinelements identical with those previously described are given likereference numerals, and their de scription is not repeated. A modifiedspring member 27 is provided which differs from spring member 21 in thatdepressed portion 26 is provided with a further projecting dimple 28which extends into a mating recess 29 formed in the contact surface ofhead 14- opposite spring 27. Dimple 28 protrudes fully into recess 29when there is no wire inserted in the test clip, and prevents a wireinserted between the spring and the head from being forced all the wayto the bottom. This extended stop portion is advantageous when it isdesired to accommodate a larger range of wire sizes than is possiblewithout the recess as well as in situations where a heavy insertionforce is to be expected from the testing personnel.

Another variation found in this embodiment is the shaping of the contactportion of spring member 27.

While the upper end of the member is again provided with the graduallyflared-out portion 25, a portion 31 immediately therebelow is bentsharply away from the contact face of head 14. A wire engaging portion32 extends generally parallel to the contact face. This configuration ofthe upper portion of spring 27 provides a gentle taper so that only asmall force is required to insert a wire, with the abrupt angle providedby portion 31 requiring a substantially greater force to pull the wireout of the clip. It will be apparent that further modifications in theshape of the contact portion 25 are readily obtainable should a specialform be desired to hold an object other than a wire. For example, theconnector of the invention can be used to hold the body or case of asmall transistor for electrical connection when the case is anelectrical element of the same.

FIG. 6 also illustrates the adaptability of bolt 13 to various mountingmeans. A standard banana plug 33 provided with an internally threadedcenter hole receives threaded portion 16 therein, and the upper surfaceof 4 the plug provides the adjustable engagement with base portion 22.

Another modification of the invention is shown in FIG. 7. In thisembodiment head 14 of bolt 13 is provided with a transversely disposedhole 34 adapted to receive a pin 35 which extends a given distance from0ppositely disposed contact faces of head 14. Two identical springmembers 37 are received on the bolt with their base portions 22overlapping. Their upper contact portions contain apertures 38 adaptedto receive the projecting pins 36 therethrough. Pins 36 thus do notinterfere with the engagement of spring members 37 against theirrespective contact faces, but do provide a positive stop for a wireinserted between the spring members and the head.

It is to be understood that spring members 21 and 27 likewise may bemounted in pairs in the manner of spring members 37. In FIG. 5 a testclip is shown having a pair of spring members 21. Since head 14 issquare shaped a total of four spring members may be mounted against thefour contact faces when it is desired to connect a plurality of Wires toone test clip.

FIG. 7 also illustrates another method of mounting the test clip. Herethe threaded stem of the clip is screwed into a panel 39, the panelitself providing the surface to bear against base portion 22 while hexnuts 17 and 18 are utilized to hold electrical connecting lug 41.

The above-described test clip thus provides a versatile electricalconnector easily adapted for a variety of applications. Due to theprovision of a rigid bolt 13 it can be made in extremely small sizessince the strength of the thinner spring members is not relied upon tosupport the assembly. The spring members are easily mounted on the boltand the mounting provides a convenient method of adjusting the tensionof the spring member against the contact face of the bolt head.Moreover, the form of the bolt may be standardized and then variousforms of spring members may be supplied as accessory items to convertthe test clip from one appli cation to another.

The clip is easily adapted for holding objects other than wire leads,and may be used simply as a fixture, either to hold a part forelectrical test or merely as a mechanical holding device. Due to itscomparatively large mass, the rigid member may also serve as a heat sinkto absorb heat away from relatively delicate components such astransistors during a soldering operation.

I claim:

1. A miniature electrical test clip for making a connection to a wireincluding in combination, a rigid conductive member having an elongatedpost portion of square cross section with substantially flat sides and areduced externally threaded lower stem portion, with the junction ofsaid post portion and said stem portion forming a shoulder therebetween,internally threaded mounting means on said stem portion, and a generallyL-shaped conductive sheet metal spring member having a bowed baseportion and a contact portion, said base portion having a holetherethrough adapted to receive said threaded stem portion for mountingsaid spring member thereon between said shoulder and said mountingmeans, with said bowed base portion convexly disposed against saidshoulder and said contact portion extending upwardly along said postportion, said bowed base portion of said resilient member being clampedand flexed between said shoulder and said mounting means to urge saidcontact portion of said spring member towards one flat side of said postportion with a force inversely proportional to the distance between saidshoulder and said mounting means, said contact portion including adepressed portion forming a projection lying against said fiat side ofsaid post portion and further including an upper flaredout portion atthe upper end thereof normally engaging said post portion with the partof said contact portion between said depressed portion and saidflared-out portion being substantially fiat, so that a wire inserteddownwardly between said side of said post portion and said flared-outportion of said spring member flexes said contact portion away from saidpost portion and the wire is then held in resilient engagement betweensaid fiat side of said post portion and said substantially flat part ofsaid contact portion, with said projection formed by said depressedportion of said contact portion underlying the wire and limiting thedownward movement thereof.

2. A test clip in accordance with claim 1 including a further L-shapedconductive spring member having a bowed base portion and a contactportion, with said base portion of said further spring member having ahole therein for receiving said threaded stem portion of said rigidconductive member for mounting said further spring member between saidshoulder and said mounting means, and said contact portion of saidfurther spring member engaging a different side of said post portion andhaving 6 an upper flared-out portion and a depressed portion with asubstantially flat part therebetween.

References Qited in the file of this patent UNlTED STATES PATENTS2,062,690 Weynand Dec. 1, 1936 2,297,036 Tallman Sept. 29, 19422,380,114 Kurillo July 10, 1945 2,458,511 Harlow Jan. 11, 1949 2,726,376Heath Dec. 6, 1955 2,761,115 Visconti Aug. 28, 1956 2,851,669 Koch Sept.9, 1958 2,853,520 Chance Oct. 28, 1958 2,997,680 Arthur Aug. 22, 1961FOREIGN PATENTS 610,463 Great Britain Oct. 15, 1948

1. A MINIATURE ELECTRICAL TEST CLIP FOR MAKING A CONNECTION TO A WIREINCLUDING IN COMBINATION, A RIGID CONDUCTIVE MEMBER HAVING AN ELONGATEDPOST PORTION OF SQUARE CROSS SECTION WITH SUBSTANTIALLY FLAT SIDES AND AREDUCED EXTERNALLY THREADED LOWER STEM PORTION, WITH THE JUNCTION OFSAID POST PORTION AND SAID STEM PORTION FORMING A SHOULDER THEREBETWEEN,INTERNALLY THREADED MOUNTING MEANS ON SAID STEM PORTION, AND A GENERALLYL-SHAPED CONDUCTIVE SHEET METAL SPRING MEMBER HAVING A BOWED BASEPORTION AND A CONTACT PORTION, SAID BASE PORTION HAVING A HOLETHERETHROUGH ADAPTED TO RECEIVE SAID THREADED STEM PORTION FOR MOUNTINGSAID SPRING MEMBER THEREON BETWEEN SAID SHOULDER AND SAID MOUNTINGMEANS, WITH SAID BOWED BASE PORTION CONVEXLY DISPOSED AGAINST SAIDSHOULDER AND SAID CONTACT PORTION EXTENDING UPWARDLY ALONG SAID POSTPORTION, SAID BOWED BASE PORTION OF SAID RESILIENT MEMBER BEING CLAMPEDAND FLEXED BETWEEN SAID SHOULDER AND SAID MOUNTING MEANS TO URGE SAIDCONTACT PORTION OF SAID SPRING MEMBER TOWARDS ONE FLAT SIDE OF SAID POSTPORTION WITH A FORCE INVERSELY PROPORTIONAL TO THE DISTANCE BETWEEN SAIDSHOULDER AND SAID MOUNTING MEANS, SAID CONTACT PORTION INCLUDING ADEPRESSED PORTION FORMING A PROJECTION LYING AGAINST SAID FLAT SIDE OFSAID POST PORTION AND FURTHER INCLUDING AN UPPER FLAREDOUT PORTION ATTHE UPPER END THEREOF NORMALLY ENGAGING SAID POST PORTION WITH THE PARTOF SAID CONTACT PORTION BETWEEN SAID DEPRESSED PORTION AND SAIDFLARED-OUT PORTION BEING SUBSTANTIALLY FLAT, SO THAT A WIRE INSERTEDDOWNWARDLY BETWEEN SAID SIDE OF SAID POST PORTION AND SAID FLARED-OUTPORTION OF SAID SPRING MEMBER FLEXES SAID CONTACT PORTION AWAY FROM SAIDPOST PORTION AND THE WIRE IS THEN HELD IN RESILIENT ENGAGEMENT BETWEENSAID FLAT SIDE OF SAID POST PORTION AND SAID SUBSTANTIALLY FLAT PART OFSAID CONTACT PORTION, WITH SAID PROJECTION FORMED BY SAID DEPRESSEDPORTION OF SAID CONTACT PORTION UNDERLYING THE WIRE AND LIMITING THEDOWNWARD MOVEMENT THEREOF.